In a conventional ink-jet printer, sheet media are directed through a print cycle which includes picking up a single medium from an input tray, feeding it to an input port and through a print zone for printing, and then expelling it through an output port. Such an ink-jet printer typically has a supply of sheet media in the input tray and an output support structure or tray for receiving paper expelled from the output port. The printer has a sheet-media drive mechanism for picking up or pulling in a single medium from the top of the input stack in the input tray. The drive mechanism includes drive rollers that contact the top sheet medium in the input tray and drive it through a print zone located generally inside the housing or chassis of the printer. After printing, the drive mechanism feeds the sheet media out the output port and onto an output tray (or other output support structure).
Generally, an ink-jet printer is capable of handling sheet media of various sizes, including standard letter size (81/2".times.11"), legal size (81/2".times.14"), various other paper sizes and narrow sheet media such as envelopes, stationary and postcards. Ink-jet printers usually have only one input source or input tray to reduce the printer's footprint, complexity and cost.
Accordingly, if a user wishes to print on a single sheet medium (e.g., an envelope or a postcard) that is narrower than the type of media already in the input tray, then the user carefully places the narrow medium on top of or in place of the sheet media in the input tray. In most ink-jet printers, printing on narrow media is done on the far right extreme of the print zone of the printer. Thus, the user must ensure that the single medium is flush to the right side of the input tray and aligned so that it enters the input port nearly perfectly straight. When a narrow medium is inserted, drive rollers catch the narrow medium and pull it into the printer. This narrow medium insertion process is annoying at best and troublesome at worst. This process causes the user to disturb or affect the sheet media in the input tray by placing the narrow medium on top of the existing sheet media or in place of the existing sheet media. In addition, the user's alignment of the single medium is likely to produce skew or misalignment.
Conventionally, sheet media used in the printers, such as an ink-jet printer, have the shape of a right rectangle where each edge of a medium is one side of the right rectangle. The sheet media have two substantially planar surfaces on which various text and graphics can be printed. Generally, it is undesirous to have the text printed on the sheet medium to be misaligned, askewed, crooked, or oblique. This problem is known to those who are skilled in the art as "skew" and is the result of a sheet medium following an oblique course or a deviation from a predetermined straight line along the input path of the printer.
The present invention provides an improved sheet media handling system which affords manual, aligned insertion of a single sheet medium without affecting the input supply of sheet media and without unduly increasing the system's size, complexity or price.